FP17.4 Acetabular Morphology and Change in Lateral Center-Edge Angle Differentially Influence 10-Year Outcomes in Traumatic Versus Atraumatic Femoroacetabular Impingement Syndrome Following Hip Arthroscopy

Abstract

Abstract ICL17 - The Full Picture: Shaping the Future of Global Hip Preservation, Ground Floor Session Room (BMCC Level 0), October 9, 2026, 14:00 - 16:00 Purpose To evaluate whether baseline hip morphology and radiographic correction differ between traumatic and atraumatic causes of femoroacetabular impingement syndrome (FAIS), and to determine whether these morphologic factors influence 10-year patient-reported outcomes (PROs) after primary hip arthroscopy (HA). Methods Patients who underwent primary hip arthroscopy for FAIS with minimum 10-year follow-up were retrospectively reviewed from a prospectively collected cohort. Patients were classified as traumatic or atraumatic based on preoperative injury history. A 2:1 propensity score match was performed using age at surgery, sex, body mass index (BMI), and baseline modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS), yielding a matched cohort of 48 patients (traumatic n=16, atraumatic n=32). Baseline radiographic variables included preoperative alpha angles, lateral center-edge angle (LCEA), Tönnis angle, Tönnis grade, head-neck angle, and overcoverage category. Radiographic correction was assessed using change in alpha angle and LCEA from preoperative to postoperative imaging. Between-group comparisons were performed with Welch’s t-tests or Fisher’s exact tests. Multivariable linear regression models were constructed to evaluate the association of baseline morphology and radiographic correction with 10-year outcomes, and interaction terms were created to assess whether these relationships differed between traumatic and atraumatic hips. Results After 2:1 matching (N=48; traumatic n=16, atraumatic n=32), groups were balanced at baseline (age p=0.936, sex p=1.000, BMI p=0.816). At 10 years, no significant between-group differences were observed in mHHS (86.9 vs 87.2, p=0.949), NAHS (84.6 vs 86.3, p=0.741), change in mHHS (39.3 vs 37.4, p=0.669), or change in NAHS (40.5 vs 41.8, p=0.793). Baseline alpha angles, Tönnis grade, head-neck angle, overcoverage category, and preoperative LCEA were not associated with differential 10-year outcomes between traumatic and atraumatic hips. Traumatic hips demonstrated lower preoperative Tönnis angle than atraumatic hips (2.4 vs 5.5, p=0.047). Change in alpha angle did not predict 10-year outcomes. In contrast, change in LCEA demonstrated a significant interaction with traumatic etiology for both 10-year mHHS (ß=-3.53, p=0.007) and 10-year NAHS (ß=-3.31, p=0.018). In atraumatic hips, greater LCEA reduction was associated with worse 10-year PROs, whereas this association was not observed in traumatic hips. Conclusion Although traumatic and atraumatic causes of FAIS demonstrated comparable 10-year PROs after hip arthroscopy, traumatic hips showed subtle, baseline features of greater acetabular coverage. The principal morphologic finding was that change in LCEA influenced long-term outcomes differently by etiology, with greater LCEA reduction associated with worse 10-year PROs in atraumatic hips but not traumatic hips.